As is well known in the art, various cardiovascular prostheses are often employed to treat and reconstruct damaged or diseased cardiovascular structures and associated tissue, such as cardiovascular vessels and heart tissue. However, despite the growing sophistication of medical technology, the use of prostheses to treat or replace damaged biological tissue remains a frequent and serious problem in health care. The problem is often associated with the materials employed to construct the prostheses.
As is also well known in the art, the optimal prostheses material should be chemically inert, non-carcinogenic, capable of resisting mechanical stress, capable of being fabricated in the form required and sterilizable. Further, the material should be resistant to physical modification by tissue fluids, and not excite an inflammatory reaction, induce a state of allergy or hypersensitivity, or, in some cases, promote visceral adhesions.
Various materials and/or structures have thus been employed to construct prostheses that satisfy the aforementioned optimal characteristics. Such materials and structures include tantalum gauze, stainless mesh, Dacron®, Orlon®, Fortisan®, nylon, knitted polypropylene (e.g., Marlex®), microporous expanded-polytetrafluoroethylene (e.g., Gore-Tex®), Dacron reinforced silicone rubber (e.g., Silastlc®), polyglactin 910 (e.g., Vicryl®), polyester (e.g., Mersilene®), polyglycolic acid (e.g., Dexon®), processed sheep dermal collagen, crosslinked bovine pericardium (e.g., Peri-Guard®), and preserved human dura (e.g., Lyodura®).
As discussed in detail below, although some of the noted prosthesis materials satisfy some of the aforementioned optimal characteristics, few, if any, satisfy all of the optimal characteristics.
Metallic mesh structures, e.g., stainless steel meshes, are generally inert and resistant to infection. Metallic mesh structures are, however, prone to fragmentation, which can, and in many instances will, occur after the first year of administration.
Synthetic mesh structures are easily molded and, except for nylon, retain their tensile strength in or on the body. Synthetic mesh structures are, however, typically non-resorbable and susceptibility to infection.
A major problem associated with Marlex®, i.e. polypropylene, mesh structures is that with scar contracture, polypropylene mesh structures become distorted and separate from surrounding normal tissue.
A major problem associated with Gore-Tex®, i.e. polytetrafluoroethylene, mesh structures is that in a contaminated wound it does not allow for any macromolecular drainage, which limits treatment of infections.
Mammalian tissue, such as extracellular matrix (ECM), is also often employed to construct cardiovascular prostheses. Illustrative are the prostheses disclosed in U.S. Pat. Nos. 3,562,820 and 4,902,508. Further ECM prostheses (i.e. multi-sheet laminate structures) are disclosed in U.S. Pat. No. 8,808,363 and Applicant's Co-Pending application Ser. Nos. 14/031,423, 14/337,915, 14/566,155 and 14/566,306, which are incorporated by reference herein in their entirety.
Although many of the ECM based cardiovascular prostheses satisfy many of the aforementioned optimal characteristics, when the ECM graft comprises two or more sheets, i.e. a multi-sheet laminate, such as disclosed in Co-pending application Ser. No. 14/031,423, the laminate structures can, and in some instances will, delaminate.
Thus, readily available, versatile cardiovascular prostheses that are not prone to calcification, thrombosis, intimal hyperplasia and delamination would fill a substantial and growing clinical need.
It is therefore an object of the present invention to provide cardiovascular prostheses that substantially reduce or eliminate (i) the risk of thrombosis, (ii) intimal hyperplasia after intervention in a vessel, (iii) the harsh biological responses associated with conventional polymeric and metal prostheses, and (iv) the formation of biofilm, inflammation and infection.
It is another object of the present invention to provide cardiovascular prostheses that modulate inflammation and induce host tissue proliferation, remodeling and regeneration of new tissue and tissue structures with site-specific structural and functional properties when delivered to damaged cardiovascular tissue.
It is another object of the present invention to provide cardiovascular prostheses that are capable of administering a pharmacological agent to host tissue and, thereby produce a desired biological and/or therapeutic effect.